Signaling system



B. H. PETER.

SIGNALING SYSTEM.

APPLICATION FILED MAY I6. 1918.

Patented Jan. 6, 1920.

INVENTOR rWITNESSESQVV 6 i d Hf m, W Q'Z-ZQM UNITED STATES PATENT OFFICE.

BERNARD HARTLEY PETER, OF WESTMINSTER, ENGLAND, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE U'NIGN SWITCI-I & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A QOREORA'IION OF PENNSYLVANIA.

SIGNALING QYSTEM.

Specification of Letters Patent.

Patented Jan. 6, 1920.

Original application filed October '7, 1914, Serial No. 865,495. Divided and this application filed May 16,

1918. Serial No. 235,018.

To all whom it may concern:

Be it known that I, BERNARD HARTLEY PETER, a subject of the King of Great Britain, residing at Westminster, England, have invented certain new and useful Improvements in Signaling Systems, of which the following is a specification.

This invention relates to railway signaling systems of the kind in which an alternating electric current for signaling purposes is supplied, to circuits constituted by the track rails, from any suitable source, such for instance as an alternating current generator or a transformer supplied thereby.

The present application is a division of my co-pending application filed October V7, 191i, Serial No. 865,495, for signaling systems.

In systems of the above kind, the track rails are usually divided into block sections, the railsof which are arranged to be shortcircuited as regards the signaling current supplied thereto when the section is occu pied by a train, the actuation of one or more of the signaling devices being arranged to be efiected in any desired manner by this means so as to indicate the presence of a train in the block section.

In order to enable both rails of the track to be employed as the return circuit for propulsion current in the case of an electrically propelled railway, it is usual to cross-connect the track rails at each end of the block section by inductive devices known as inductance bonds, the middle or other intermediate points in the windings of each bond being connected to a corresponding point in the winding of the bond in the next adja cent block section.

The function and operation of these inductance bonds is now well known and need not be further described, but it will be understood that the winding of the bond serves as adirect electrical connection between the two track rails as regards direct current, while maintaining the two rails at clifferent alternating current potentials for signaling purposes.

In order that the reactance of the inductance bonds may be as great as possible as far as alternating currents are concerned, it has previously been proposed to provide the bonds with a continuous magnetic circuit or core thus enabling a magnetizing current of relatively small amount to create a large magnetic flux in the core of the bond owing to its low magnetic permeability, thereby insuring a sufficiently high reactive electro-motive force. This construction is however open to the disadvantage that the direct propulsion current passing through the winding of the bond is also capable of creating a large magnetic flux owing to the low reluctance of the continuous magnetic core, and although the direct currents flowing in the two parts of the winding of the bond on either side of the middle or intermediate point above referred to are in op posite directions, any unbalancing of the current in the two track rails will necessarily cause a magneto-motive force to be set up which, in view of the low reluctance of the magnetic circuit of the bond, may easily cause magnetic saturation of the core. If this condition occurs, the bond will evidently cease almost entirely to respond to the alternations of the signaling electro-motive force and only a very small amount of reactive electro-motive force will. be developed in the winding of the bond which is thus rendered inoperative for the purpose for which it is intended.

In order to overcome this disadvantage it has also been proposed to provide the magnetic circuit of the bond with an air gap so as to reduce its permeability and thereby prevent magnetic saturation as above described. This construction, however, is open to the further disadvantage that the permeability of the magnetic circuit of the bond is reduced for alternating current magnetization also, and consequently a considerably increased magnetizing alternating current is necessary which must evidently be supplied from the source of signaling current. As the magnetizing current is almost entirely wattless, it represents a very unfavorable load on the alternating current generator or other source of signaling current, and the present invention has for its object to provide an improved arrangement whereby inductance bonds having air gaps in their magnetic circuits may be employed without at the same time imposing a load of low power factor upon the source of signaling current.

According to the present invention the circuit of the bond is arranged to be inductively related to a resonant circuit, that is to say, to a circuit containing such an amount of capacity or condensance relative to its inductance that a condition of resonance is partly or completely obtained.

In the accompanying drawings, Figure 1 is a diagrannnatic view of a portion of two block sections, the adjacent ends of the sections being bridged by means of impedance bonds. Figs. 2 and 3 are similar views illustrating two different embodiments oi my invention.

Similar reference characters refer to similar parts in each of the views.

In each of the views the rails l and 2 are connected together by means of impedance bonds 3 in the usual and well known manner. 7

In the embodiment of my invention shown in F ig. 2, the terminals of the bond 3 are connected to the primary winding 5 of the transformer, the secondary winding 6 of which is closed on itself through a condenser 7 the capacity of the condenser being such that the inductance of the whole circuit including the primary and secondary windings or the transformer and the impedance bonds constitute with the condenser a resonant circuit. The wattless component of the magnetizing current required for the bond will thus be constituted by the resonant currents sur ing into and out or the condenser in the well known way, and the only current required to be supplied to the track circuit will be that corresponding to the true watt loss in the track rails and the impedance bonds.

In the arrangement illustrated in Fig. 3, the condensers are connected in parallel with each impedance bond.

-t will be understood that the ratio or" the number of turns of the primary and secondary windings of the transformer in Fig. 2 may be varied as desired, the object of the transformer being to reduce the capacity of the condenser required by increasing the voltage impressed on its terminals.

Furthermore, the amount of capacity or condenser-nee employed may, if desired, be such as to exceed that corresponding to the inductance of the bond, so as to enable the circuit of the bond to take a leading current and thereby compensate for the inductance of the other part of the circuit, such, for instance, as the track rails themselves.

Although I have herein shown and described only two arrangements embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a railway signaling system, the combination of a track section, a source of signaling current connected across the rails of said section, an inductance bond also con.- nected across said track rails, and means associated with the bond which takes a wattless current leading the voltage, and which wattless current is in multiple with the current required to magnetize the bond.

In a railway signaling system, the combination of a track section, a source of alternating signaling current connected across the rails of said section, an inductance bond also connected across said track rails, a step-up transformer having its primary connected across the terminals of said bond, and a condenser connected with the second ary of said transformer.

In testimony whereof I aiiix my signature in presence ot two witnesses.

BERNARD HARTLEY PETER.

Witnesses:

ARTHUR James HALL, R. BAGGAT. 

